A system and method for controlling a train, and in particular, a system and method of controlling a train by determining the location on the route.
In radio-controlled travel operation, setting and securing route elements which are conventionally assigned to a signal box are distributed exclusively among local route element computers and vehicle-mounted computers (Signal+Draht [signal and wire] 4/99, pp 18-22). The operating states of the route elements and the positions of the vehicles on the route are visualized in a control center. In order to carry out a train journey, a traffic controller assigns a route to a train at its request by radio transmission. The assignment of the route includes a list of logic route sections which authorizes the train, and only this train, to travel along these route sections. Once a route assignment has been made, it continues to apply until it is completed or until it is rescinded. To safeguard the sequence of trains, neither signals nor intermittent train control devices are required. Rather, there is no need either for conventional track surveillance by means of axle counters or DC circuits because the trains themselves determine their respective travel location. Hence, the trains detect whether they are still located in the sections assigned to them, and detect the latest time at which they are to request new, updated route assignments and when they have to begin braking if such updated route assignments are not obtained. The system of radio-controlled travel operation provides protection against rear-end collisions, opposing collisions and slanting collisions of trains which are equipped with corresponding communication means. These collisions are prevented by braking curves at the limits of route sections and at hazard points. Route elements are preferably switches and railway crossings. The term train is used throughout this disclosure to describe both individual vehicles, as well as formations of vehicles formed from a plurality of individual vehicles.
The satellite is located at a position suitable for the trains to find their own location in the track network. The system is economical, reliable and subject to a relatively small locating error which can be reduced by additional means, for example fixed locating points arranged on the track. However, for a train to find its own location on a line, more than a satellite locating system is necessary. Instead, a route atlas (which reproduces the route with sufficient precision) is necessarily located in the train in radio-controlled travel operation mode so that the train can determine whether it is located within the travel sections assigned to it and precisely where it is located. Additionally, the vehicles have to convert their local positions acquired from the satellite locating method to the coordinates of their route atlas in order to find their way in the railway network.
In extensive railway systems, for example in North America or in Australia, there is the need (for cost reasons) to manage without such route atlases on the trains. Rather, the trains use exclusively satellite locating methods for determining their own position and for determining their travel location on the line. Hence, there should be no need for track-mounted infrastructure for carrying out the location-determining process on the track, as is also the case in radio-controlled travel operation.
In one embodiment of the invention, there is a method for controlling a train. The method includes, for example, assigning a route area to the train for which it is to travel, wherein the route area in which the train is to travel is a route polygon which covers a location of the train and a destination in the route area and within which the train has to stop; setting up a location space around the location of the train, the location space defined by a confidence interval of a location-determining process and a stopping distance; and braking when the location space touches, intersects or lies outside the polygon line of the route polygon.
In one aspect of the invention, the route polygon and the location space are defined as coordinates of a common coordinate system.
In another aspect of the invention, the train determines the location coordinates based on a satellite locating system.
In still another aspect of the invention, the location space to be set up by the train is defined as a polygon.
In yet another aspect of the invention, the destination of the train is predefined by the control center by two of the coordinates which define a straight line which intersects the track to be traveled along at the destination.
In another aspect of the invention, in order for the train to continue beyond the route polygon, the control center prescribes for the train a connecting route polygon which covers the destination of the previous route polygon.
In still another aspect of the invention, adjacent route polygons are logically linked by the two coordinates for the start and the destination of a train journey.
In another embodiment of the invention, there is a device for controlling a train. The invention includes, for example, a control center which assigns a route area in which the train is to travel; at least one route control center to prescribe a route polygon which covers a location of the train and a destination of the train in the route area and in which the train has to stop; and a vehicle-mounted unit to inform the train about the route polygon which is to be traveled along, and which is configured to set up the location space about the travel location determined by the train, the location space being dependent on a confidence interval of a location-determining process and a stopping distance of the train, the vehicle-mounted unit initiating the braking process if the location space touches, intersects or lies outside of the route polygon.